I am interested in using the Arduino Due in a Wifi network. Can anyone suggests what I should purchase besides the board to get it up and running, i.e. shields, power supplies, connections, etc. I just don't want to get the board and not be able to put it in our network.

You can put together a package with a openwrt router talking to the due over a serial port. While you have limitations on the speed of the serial port you get a fully functional WiFi connection. I like carambolas but there are several openwrt boards you can use. You end up with a high powered yun. There is lots of info on what you can do in the yun http://forum.arduino.cc/index.php?board=93.0